Self-cleaning spark-plug.



W. H. COTTDN.

SELF CLEANING SPARK PLUG. APPLICATION nun-Aug; 16, ms.

1,238,990. Patented Sept. 4, 1917.

UNITED STATES PATENT OFFICE.

WALTER H. COTTON, OF CHICAGO, ILLINOIS,

DIG 00., F HURON, SOUTH ASSIGNOB TO OLD DUTCH MANUFACTURE DAKOTA, ACORPORATION.

SELF-CLEANING SPARK-PLUG.

Specification of Letters Patent.

Application filed August 10, 1916. Serial No. 115,183.

devices for internal combustion engines and contemplates a constructionby which a vigorous movement of the gases over'the electrodes andadjacent parts is insured. The object of the invention is to provide aspark plug for explosive engines which shall be of simple constructionbut reliable in operation under all circumstances.

The invention is exemplified by the structure to be hereinafterdescribed and which is illustrated in the accompanying drawings wherein,

Figure 1 is a sectional view showing ofie form of the section beingindicated by the line 1'1 on Fig. 3, and some of the parts being shownin elevation;

Fig. 2 is a side elevation spark plug;

Figs. 3 and 4 are a top plan view and an inverted lan view,respectively, and

Fig. 5 1s a detail sectional view of an explosive engine showing one wayin which the improved spark plug maybe applied thereto, the spark plugbeing shown in elevation. v

The construction preferably comprises a chambered body having acontracted tubular stem 11 at one end. The stem 11 may be externallythreaded for introduction into the spark plug socket 12 of an explosivemotor, as 13, in a well known manner. One of the electrodes, as 14, ismounted at the outer end of the tubular stem 11 andprojects over thebore 15 of the stem to a point adjacent its axis, as usual. The otherelectrode, as 16, may also be of familiar construction. As shown, ittakes the form of a straight rod or wire, axially rranged with referenceto the stem 11, diid extending upwardlythrough the body 10, with thegreater portion of the wire cmof the improved of the improved sparkplug, the plane bedded in an insulating cylinder 17, ofhard material, asporcelain, and with the usual binding screw 18 provided at the upperend.

In the preferred form of construction, as illustrated in the drawings,the electrode 16 and its insulating cylinder 17 are removably mounted topermit of their being separated from the body 10.

For this purpose the insulating cylinder 17 is formed with an annularlyenlarged portion 19 intermediate its ends providing oppositely facingshoulders 20 and 21.. To provide a compact arrangement, the cover 22 ofthe body 10 is formed with a depressed central portion 23 which servesasa socket for receiving the enlarged portion 19 of the insulatingcylinder 17. Under these circumstances the floor of the socket 23 isapertured as at 24, to permit the. passage of the electrode 16 and thepart of the insulating cylinder 17 which is below the enlargement 19. Inassembling the parts, gaskets 25, 26, are applied to the two shoulders20 and 21 and a screw plug 27 is entered in the socket 23 over theuppermost gasket, as

For convenience in manufacture, the cover 22 may be formed from aseparate piece but it is permanently united with the side walls of thebody, as by welding.

When the parts are proportioned about as shown, the chamber of the body10 about the socket 23 constitutes a pocket into which the gases arecompressed at intervals and from which they escape by expansion when thepressure is released. As the space surrounding the insulating cylinder17 within the bore of the stem 11 provides only a re stricted passagefor the gases to and from the body chamber, the movement of the gasesover the surface of the insulating cylinder 17.adjacent the exposed partof the electrode 16 will be sufiiciently vigorous to provide that thissurface will be swept clean of any deposit of material likely to cause apath for the electric charge. Ger.- tainty in operation is therebyinsured.

I claim as my invention,

1. A s ark plug having a metal body and a core 0 insulating materialinclosd in the Patented Sept. 4, 1917.

body. such body being provided with an annular chamber surrounding thecore and stantiel length, and a pair of coo crating electrodes, onethereof projecting mm the core.

2.- A spark plug having a chambered body and a tubular neck open at itsouter end, the bore of the neck communicating with the chamber of thebody and being of less diameter than such chamber, a core of insulatingmaterial extending into the bore of the neck and forming With the Wallthereof a restricted annular passage of substantial length, and a pairof cooperating terminals one thereof projecting through the core.

3. A spark plughaving a hollow metal body open at its inner end, theinner end of the chamber of the body being enlarged, a core ofinsulating material on the axis of the body and extending a substantialdistance into the restricted portion of the body chamber and formingwith the wall thereof an annular axially directed passage from theenlarged portion of such chamber, and a pair of cooperating electrodesone thereof projecting from the core.

WALTER H. COTTON.

